code: def __init__(self):
      self.node_counts = []
  
file_path: ray/release/cluster_tests/workloads/tune_scale_up_down.py
imports: from collections import Counter
  import time
  import ray
  from ray import train, tune
label_desc: Use image node_id 1 to create a new NodeCountCallback object from inherited base classes: tune with example: obj = NodeCountCallback()